Medical devices can include devices designed to be implanted into a patient. Some examples of these implantable medical devices (IMDs) include cardiac function management (CFM) devices such as implantable pacemakers, implantable cardioverter defibrillators (ICDs), and cardiac resynchronization therapy devices (CRTs). The devices can be used to treat patients or subjects using electrical or other therapy or to aid a physician or caregiver in patient diagnosis through internal monitoring of a patient's condition. The devices may include one or more electrodes in communication with one or more sense amplifiers to monitor electrical heart activity within a patient, and often include one or more sensors to monitor one or more other internal patient parameters. Other examples of IMDs include implantable diagnostic devices, implantable drug delivery systems, or implantable devices with neural stimulation capability.
Medical devices can also include wearable medical devices (WMDs) such as wearable cardioverter defibrillators (WCDs) and wearable diagnostic devices. WCDs are monitors that include surface electrodes. The surface electrodes are arranged to provide one or both of monitoring surface electrocardiograms (ECGs) and delivering cardioverter and defibrillator shock therapy. Medical devices can of course also be stationary devices to provide diagnostic capability and therapy to bedridden or otherwise less mobile patients.
Some medical devices include one or more sensors to monitor different physiologic aspects of the patient. Patient posture can be sensed with a posture sensor. Sensing of patient posture can provide information related to a patient's condition or disease. For example, a patient with congestive heart failure (CHF) may tend to sleep in an upward position as their condition worsens. Patient posture information may also be useful in other aspects of patient monitoring. For example, physiologic measurements taken by a medical device may vary with patient posture. Knowledge of the posture of the patient during the measurements may be useful to a caregiver in interpreting the device-based measurements.